Invasive alien species: a rising global threat that needs control
Authors: Stephanie Margarete Thomas
Journal: The Lancet Planetary Health (2023)

Invasive alien species have at last received the global attention required to substantially mitigate their negative effects on biodiversity, health, water, and food security. A new report from the Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES) estimated that such species caused economic loses of US$423 billion globally in 2019. Of the more than 37 000 alien species that have been introduced through various human activities, more than 3500 of these are harmful invasives. Approximately 200 new alien species are recorded annually. A multidisciplinary team of 86 experts from 49 countries, along with more than 200 contributing authors, reviewed more than 13 000 documents to produce the Thematic Assessment of Invasive Alien Species and Their Control for IPBES.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar This assessment was finalised after intense week-long negotiations in Bonn, Germany, and was subsequently approved by 143 governments. Notably, at the onset of these discussions, there was no unanimously agreed-upon terminology for invasive alien species despite 4 years of collaborative effort. This highlights the complexity of the issue. The summary for policy makers now presents an internationally agreed definition while it acknowledges that national and local legislations have varying definitions when addressing biological invasions. The agreed definition for invasive alien species—ie, a species that is either intentionally or unintentionally transported by human activities outside its natural range, is already established and spreads to a new area, and has a negative impact on species and ecosystems in the new region—will hopefully simplify international cooperation for an effective implementation of management and control measures in the future. A very important (and unfortunately, often unique) aspect of these intergovernmental negotiations was the incorporation of diverse values and knowledge systems. These included insights from scientific literature, indigenous populations, and local knowledge holders. Through this inclusive approach, numerous facts and examples of previously overlooked issues related to invasive alien species were brought to light. The assessment emphasises four key messages. First, that invasive alien species are a major threat to nature, nature's contributions to people, and overall quality of life.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Second the spread of invasive alien species and their impacts are accelerating globally and are expected to intensify in the future.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Third, the detrimental effects of these species can be prevented and mitigated through effective management.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar And finally, substantial progress to manage biological invasions can be achieved through integrated governance with closer collaboration across sectors and countries.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Invasive alien species threaten livelihoods, water and food security, economies, and human health. For example, infectious zoonotic diseases such as dengue fever, Chikungunya, Zika, and yellow fever, are spread by invasive mosquito species like Aedes albopictus that originated in southeast Asia but are now established on all continents except Antarctica.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar, 2Diagne C Leroy B Vaissière AC et al.High and rising economic costs of biological invasions worldwide.Nature. 2021; 592: 571-576Crossref PubMed Scopus (498) Google Scholar Invasive alien plants can also impact human health—for example, through the production of highly allergenic pollen causing hay fever, asthma, and allergic dermatitis (eg, Ambrosia artemisiifolia or common ragweed).1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Within the freshwater ecosystem, the invasive water hyacinth (Pontederia crassipes) is able to double its biomass in 1–2·5 weeks, reducing habitat biodiversity through decreasing oxygen levels and thus harming native fish populations and degrading waterfowl habitats.3Global Invasive Species DatabaseSpecies profile: Eichhornia crassipes.http://www.iucngisd.org/gisd/species.php?sc=70Date: 2023Date accessed: October 6, 2023Google Scholar Additionally, invasive alien species represent the most significant threat to natural World Heritage sites, affecting 68 of the 241 sites.4Osipova E Emslie-Smith M Osti wM Murai M Åberg U Shadie P IUCN world heritage outlook 3: a conservation assessment of all natural World Heritage sites.https://portals.iucn.org/library/sites/library/files/documents/2020-035-En.pdfDate: 2020Date accessed: October 15, 2023Google Scholar There are various introductory pathways for these species, for example, through their use for feeding livestock, planting of non-native trees, as ornamental plants or pets, or even accidentally in emergency relief and aid. The invasive parthenium weed—originating in South America and central America and used in enzyme production and as an additive in biogas production—was most likely introduced to India via food grain shipments between 1950s and 1960s from the USA.5Kohli RK Batishj DR Singh HP Dogra KS Status, invasiveness and environmental threats of three tropical American invasive weeds (Parthenium hysterophorus L., Ageratum conyzoides L., Lantana camara L.) in India.Biol Invasions. 2006; 8: 1501-1510Crossref Scopus (210) Google Scholar Serious yield losses (eg, in grain sorghum) even at low densities of the weed are now the consequences for surrounding countries (eg, in Pakistan).6Bajwa A Nawaz A Farooq M Chauhan B Adkins S Parthenium weed (Parthenium hysterophorus) competition with grain sorghum under arid conditions.Expl Agric. 2020; 56: 387-396Crossref Scopus (8) Google Scholar Indigenous Peoples and local communities often have a good understanding of how complex interactions among various drivers facilitate the introduction and spread of invasive alien species in their lands.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Beyond the aforementioned negative effects, invasive alien species can also restrict access to traditional lands, curtail the mobility of Indigenous Peoples and local communities, and necessitate increased labour for land management.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Moreover, these species can result in the loss of traditional livelihoods, knowledge, and cultural practices among these communities.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar The IPBES report encapsulates the vast body of existing knowledge and highlights the knowledge gaps concerning invasive alien species, thereby laying the foundation for concerted interventions across the affected sectors. A substantial challenge lies in the willingness of governments to earnestly address the issue of these species. It is imperative that governments undertake sustainable and effective measures to manage and control invasive alien species promptly. Alarmingly, assessments reveal that 83% of countries lack specific national legislation or regulations concerning such species.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Even when such legislation is in place, such as the Invasive Alien Species list of the European Union (regulation 1143/2014), it can lack effectiveness. This is particularly evident when species are listed based solely on their potential impact on biodiversity or ecosystem services, relegating impacts on human health or economy as mere secondary considerations. A case in point is the mosquito vector Ae albopictus, which remains unlisted due to the absence of evidence showing its negative effect on biodiversity or ecosystem services (as per personal communication with the invasive alien species team of the EU commission). To address these issues, IPBES recommends several strategic actions, including coordination and collaboration across international and regional frameworks; the development of effective national implementation strategies; shared efforts, commitments and understanding of specific roles of all actors; improving policy coherence; engaging with governmental sectors, the industrial sphere, scientific communities, Indigenous Peoples, local communities, and the broader public; funding and promoting innovative research and environmentally conscious technology; and strengthening information systems, infrastructure, and data sharing.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Under a business-as-usual scenario, IPBES anticipate a 36% increase in alien species by 2050 compared with 2005.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Furthermore, the economic repercussions of biological invasions are predicted to quadruple every decade.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar Proactive and decisive action is crucial to curtail the adverse effects of invasive alien species. The greater than 60% success rate of biological control programmes aimed at invasive alien plants and invertebrates should inspire future endeavours.1IPBESRoy HE Pauchard A Stoett P Summary for policymakers of the thematic assessment report on invasive alien species and their control of the intergovernmental science-policy platform on biodiversity and ecosystem services. IPBES secretariat, Bonn, Germany2023Google Scholar It is vital to recognise the nexus between biodiversity, and the health of environment, ecosystems, animals, and humans as we shape our strategies moving forward. I received travel grants from the University of Bayreuth, Germany, to attend author meetings of the IPBES nexus assessments and the IPBES10 plenary.